1. Field of the Invention
The present invention relates to optical disc access control, and more particularly, to methods and devices for controlling access to an optical disc.
2. Description of the Related Art
A conventional optical disc device typically comprises a closed loop generating a channel bit clock for accessing an optical disc. According to the related art, the closed loop is implemented as a phase locked loop (PLL). For example, in a reading procedure of the optical disc device, the PLL receives a data signal derived from the optical disc, and utilizes the data signal as a reference signal for the operation of the PLL. As the data signal is read from the optical disc and the PLL generates the channel bit clock by utilizing the data signal as the reference signal, and as the optical disc device reads the data signal from the optical disc based on the channel bit clock, it is indeed a closed loop and the control thereof requires many high accuracy components. As a result, a tradeoff between reducing the costs of the conventional optical disc device and preventing the closed loop control from being degraded is introduced.
In another example, when the optical disc is a Rewritable disc with wobbles pre-grooved on the optical disc, the wobbles typically carry certain disc information and address information. The PLL receives a wobble signal derived from the optical disc in accordance with the wobbles, and utilizes the wobble signal as the reference signal for the operation of the PLL. As the wobble signal is read from the optical disc and the PLL generates the channel bit clock by utilizing the wobble signal as the reference signal, and as the optical disc device utilizes the channel bit clock to access the optical disc, it is indeed a closed loop and the control thereof also requires many high accuracy components. Similarly, the above-mentioned tradeoff is again introduced.
In order to reduce the costs of the conventional optical disc device, a novel method is therefore required for reducing the costs of the products without lowering the performance, in order to benefit both the end users and the manufacturers.